Μελέτη της ηλεκτροχημικής οξείδωσης χρωμάτων αντίδρασης σε υδατικά συστήματα και πραγματικά απόβλητα

by Irina Voinovschi

Institution: Aristotle University Of Thessaloniki (AUTH); Αριστοτέλειο Πανεπιστήμιο Θεσσαλονίκης (ΑΠΘ)
Year: 2016
Keywords: Πολυαρωματικές ενώσεις; Χρώματα αντίδρασης; Ηλεκτροχημική οξείδωση; Ταυτοποίηση προϊόντων διάσπασης; Polyaromatic compounds; Reactive dyes; Electrochemical oxidation; Identification of degradation products
Posted: 02/05/2017
Record ID: 2064410
Full text PDF: http://hdl.handle.net/10442/hedi/38416


This PhD thesis presents a research oriented to develop an eco-friendly approach, at a competitive cost, for the treatment of textile wastewater. The main goal was to optimize electrochemical oxidation in order to reduce pollution and volume of the effluents with the possibility of recycling treated wastewater before discharge. Initially, electrochemical oxidation of the commercial reactive dyes (Reactive Black 5, Reactive Red 195, Reactive Blue 19 and Reactive Yellow 145), decolouration and mineralisation have been evaluated by comparing the efficiencies of two anode materials: boron doped diamond (BDD) and titanium-based dimensionally stable anode (DSA). Different electrochemical effective parameters and their impact on the electrochemical process have been investigated. The performance of the electrodes has been considered by measuring the time evolution of the colour removal, COD, TOC, on-line measuring CO2 generation, ion chromatography analyses and current efficiency. The degree of mineralization was determined by both, measurement of TOC decay and on-line monitoring of the generated CO2. Additionally, the amount of electrogenerated oxychloro species were measured and compared at both anodes. Almost complete mineralization of the azo dye has been achieved on BDD, while the efficiency of DSA was limited. Spectrophotometric techniques (UV-VIS, FTIR) were applied for the monitoring of colour removal with a rough estimation of degradation products and intermediates. The intermediates and degradation products of the azo and anthraquinone dye formed during electrochemical treatment of model solutions were identified by LC-ESI-MS. The obtained results confirmed the potential of the method to break the large, non-biodegradable polyaromatic dye molecules into smaller biodegradable compounds.Finally, in order to test the process in real conditions, two types of concentrated wastewater (reactive and acid) were obtained from a Greek dyeing house, directly from the dyeing machines, without any dilution or other preparation step and used directly for experiments. Unlike model solutions, in real textile acid wastewater no significant differences in the trend of the COD removal with BDD and DSA were observed. The performance of the anodes in conditions of high NaCl concentrations in reactive dyebath, was very similar to those obtained in model dye solutions, with limited efficiency observed at DSA. The effect of operating time and current density on the process performances and electrical energy consumption was similar with both BDD and DSA electrodes. Considering that conventionally the treatment of effluents is applied for the whole wastewater of the mill, where the total dilution is high, colour removal from the most concentrated exhausted dyebaths and recycling of the treated wastewater could reduce the consumption of fresh water for the processing, hence, has the potential to modify the current flowsheet of dying houses. H παρούσα διδακτορική διατριβή παρουσιάζει μία έρευνα με σκοπό την ανάπτυξη μιας φιλικής προς το…